Interphasic organism

From Memory Alpha, the free Star Trek reference.

Interphasic organisms are lifeforms that exist in a different phase than the rest of the universe. Though not visible to the naked eye, interphasic organisms can be seen with the use of an interphasic scanner.

In 2370 the USS Enterprise-D was infested with interphasic organisms which fed on the cellular peptides of humanoid cells. The organisms were eventually removed by Lieutenant Commander Data, who was able to emit an interphasic pulse. (TNG: "Phantasms")